Add startIndex to bigquery.table.Table.fetch_data

[kylemcdonald]

The API describes a startIndex parameter for the "Tabledata: list" endpoint. But the implementation doesn't include this parameter. An example of a class does implement a startIndex parameter is bigquery.query.Query as described in the "Jobs: getQueryResults" endpoint.

I tried editing the code to submit a PR, but I'm not familiar with testing this kind of Python package locally (pip install -e . didn't install the packages from their local copy as I expected). In lieu of a PR I can share this patched class TableWithStartIndex that works for my use case:

from google.cloud.bigquery.table import Table, _item_to_row, _rows_page_start
from google.cloud.iterator import HTTPIterator
class TableWithStartIndex(Table):
    def fetch_data_with_start_index(self, max_results=None, page_token=None, client=None, start_index=None):
        client = self._require_client(client)
        path = '%s/data' % (self.path,)
        extra_params = {}
        if start_index is not None:
            extra_params['startIndex'] = start_index
        iterator = HTTPIterator(client=client, path=path,
                                item_to_value=_item_to_row, items_key='rows',
                                page_token=page_token, max_results=max_results,
                                page_start=_rows_page_start,
                                extra_params=extra_params)
        iterator.schema = self._schema
        # Over-ride the key used to retrieve the next page token.
        iterator._NEXT_TOKEN = 'pageToken'
        return iterator

I added three small chunks: the start_index=None argument, this block:

        extra_params = {}
        if start_index is not None:
            extra_params['startIndex'] = start_index

And the bit that passes the extra_params to the HTTPIterator: extra_params=extra_params.

[lukesneeringer]

Thank you for opening the issue. We will look into it and get back to you soon.

[tswast]

Fixed by #4245.

The new Client.list_rows function takes an optional start_index parameter.